SCB and SC series transformers are both three-phase cast resin dry-type transformers, widely used in power distribution systems, industrial plants, and commercial buildings.
Although they belong to the same category, there are significant differences in winding structure, temperature rise, loss performance, insulation strength, and short-circuit resistance.
This article explains the key differences between SCB transformers and SC transformers in detail.
1. Difference in Winding Structure
The biggest difference between SCB and SC series transformers lies in the low-voltage winding design.
SCB Series – Copper Foil Winding
SCB transformers use copper foil winding for the low-voltage coil.
Features:
- Single-layer copper foil winding
- Epoxy resin with curing agent used between layers
- High-purity oxygen-free copper (≥99.99%)
- Copper foil thickness usually < 0.1 mm
Advantages:
- Better heat dissipation
- Lower loss
- Higher mechanical strength
- Improved short-circuit resistance
SC Series – Wire Wound Coil
SC transformers use wire-wound cylindrical coils.
Features:
- Cylindrical winding structure
- Multiple glass-fiber insulated flat copper wires
- Standard electrolytic copper (~99.96%)
Compared with SCB:
- More winding layers
- Harder heat dissipation
- Higher copper loss
2. Temperature Rise Difference
The low-voltage winding is close to the core, so cooling performance is critical.
SCB transformer advantages:
- Foil winding allows larger cooling surface
- Easier air circulation
- Better ventilation design
- Lower temperature rise
Typical result:
SCB temperature rise is about 5–7 K lower than SC.
Benefits:
- Higher overload capacity
- Longer service life
- Better thermal stability
3. Load Loss Difference
SCB transformers use oxygen-free copper foil, which has:
- Higher conductivity
- Fewer impurities
- Lower resistance
Result:
- Lower copper loss
- Lower additional loss caused by skin effect
For the same rating and voltage level:
SCB load loss is typically about 5% lower than SC.
4. Insulation Performance Difference
SCB foil winding has:
- Small voltage gradient between layers
- Larger inter-turn capacitance
- Higher dielectric strength
Advantages:
- Stronger insulation
- Better lightning impulse resistance
- Better over-voltage withstand capability
This makes SCB transformers more suitable for:
- High-rise buildings
- Data centers
- Hospitals
- Critical power systems
5. Short-Circuit Withstand Capability
SCB transformers perform better under sudden short-circuit conditions.
SCB Advantages
- Foil winding with large current area
- Same height for LV and HV winding
- Smaller axial force during short circuit
- Strong mechanical strength
SC Disadvantages
- Multi-wire winding creates larger leakage field
- Strong axial force at winding ends
- Higher risk of deformation under short circuit
Result:
SCB transformers have:
- Better short-circuit strength
- Higher reliability
- Longer lifetime
6. Size, Weight, and Capacity
Compared with SC:
SCB transformers usually have:
- Smaller size
- Lighter weight
- Higher capacity per volume
- Better overload capability
- Higher insulation level
Originally SCB was used mainly for special transformers
(such as excitation transformers),
but today it is increasingly used for standard distribution transformers and is considered the future development trend.
7. Summary – SC vs SCB Transformer
| Item | SC Transformer | SCB Transformer |
|---|---|---|
| Winding type | Wire winding | Copper foil winding |
| Copper purity | ~99.96% | ≥99.99% |
| Temperature rise | Higher | Lower |
| Load loss | Higher | Lower |
| Insulation strength | Normal | Higher |
| Short-circuit strength | Medium | Strong |
| Size / weight | Larger | Smaller |
| Overload capacity | Normal | Better |
| Application level | Standard | High-performance |
Conclusion
Both SC and SCB series are reliable dry-type transformers, but:
- SC → standard applications
- SCB → high-performance applications
Due to better cooling, lower loss, and higher reliability,
SCB foil-winding dry-type transformers are becoming the preferred design in modern power distribution systems.